The invention is based on a rotary angle encoder for controlling a drive unit for control devices.
There are rotary angle encoders for electric control devices or regulating devices, for example like the ones used for electric motor adjustments of throttle valves of internal combustion engines. A coupling part of the rotary angle encoder can be adjusted by a gas pedal coupled to it.
There are rotary angle encoders (DE-A-34 11 455) with a first sensor part disposed fixed in a housing and with a second sensor part, which is supported so that it can rotate in relation to the housing or the first sensor part and which can be adjusted in the direction of rotation via a coupling connected to the gas pedal. Depending upon the relative position of the second sensor part in relation to the first sensor part, the rotary angle encoder generates a sensor signal via an electrical line, which signal can be supplied to an electronic evaluation device.
In a rotary angle encoder, it is particularly important that when the coupling is disposed in a starting position, the sensor signal has a particular, defined value. Often, the sensor signal is defined so that when the coupling is disposed in its starting position, the initial signal is zero.
In the known rotary angle encoder, the second sensor part is connected to a rotary shaft on which a conical fluting is provided. When assembled, the coupling part is pressed against the fluting via a nut. To adjust the rotary angle encoder, this nut is loosened and the coupling is rotated in relation to the rotary shaft until the sensor signal has the desired value in the particular starting position of the coupling part. After the adjustment of the rotary angle encoder, the nut is tightened so that the coupling part is fixed in relation to the second sensor part.
The known embodiment has the particular disadvantage that the nut eventually loosens. Furthermore, subsequent improper manipulations and changes of the adjustment can easily occur.
Incidentally,this kind of adjustment is not particularly easy and in large-scale mass production, requires an expenditure which should not be ignored.
The rotary angle encoder embodied according to the invention has the particular advantage over the prior art of an essentially more reliable, simpler, and better potential adjustment.
The rotary angle encoder advantageously permits a structural form which is easy to assemble and reasonably priced. The rotary angle encoder can be advantageously embodied so that only detent connections or press connections are required. Problematic screw connections can be eliminated.
Advantageous updates and improvements of the rotary angle encoder are possible as a result of the steps taken herein.
Providing a cylindrical shaft either on the second sensor part or on the coupling produces a simple, advantageous possibility for adjusting the coupling part in relation to the second sensor part, from the first position into the second position.
By providing a frictional, non-positive connection between the coupling and the second sensor part in the first position, a relative rotation of the second sensor part in relation to the coupling part can advantageously be easily achieved and by providing a positively engaging connection between the coupling part and the second sensor part, the advantage is achieved that in the second position, an unintended relative rotation of the coupling part in relation to the second sensor part is reliably prevented.
The use of the cylindrical shaft to support the second sensor part and the coupling part essentially simplifies the construction of the rotary angle encoder.
In a particularly simple manner, the snap device prevents an unintended adjustment of the relative position of the coupling part in relation to the second sensor part, from the second position into the first position.